The Seas Exotic F8 full range drivers

Introduction

Whenever I visit audio shows, or hear new systems in other places,
there are certain things that will always catch my ear. Full range
drivers often appeal to me because of their directness and sweet,
musical presentation. The flip side is that most of them don't produce
much bass, even if they are mounted in large horn enclosures. Now that
we're on the topic of enclosures: one other thing that always sounds
good to me is a sealed enclosure. I've really never heard a ported
speaker, or transmission line, that sounds as tight and precise in
the bass as a sealed box, perhaps only with some very expensive
exceptions. A port might produce more bass, but since it is just
a resonator added to the driver it will also add some delays and
other problems.

A combination of these two properties would be great, but I didn't
think a full range driver that worked in a sealed enclosure existed.
Then SEAS introduced one last year, the Exotic F8. Actually, SEAS already
produced full range drivers in the early 1950's, so it's not something
new to them at all, but they do claim that their experience and modern
laboratory development tools have allowed them to produce the most
advanced full range driver available in the market today. The name
Exotic is probably well chosen, as the main cone is partly made out of
papyrus and the magnet is made out of Alnico, which has the
reputation, in some audiophile circles, of adding magic to the sound.
The Alnico name comes from Aluminium, Nickel & Cobalt, which are the
main components of this relatively expensive magnetic material. The
magnet is certainly small, which should help prevent the sound
reflecting back from it. The driver is designed to give bass response
from just below 50 Hz in a 60 litre enclosure, enabling a proper
bottom end in a larg-ish floor standing loudspeaker. Because this bass
is coming from a sealed box it should be very clean en well
controlled, which usually makes it easier to add a subwoofer, if
needed.

The only problem with this attractive driver is that it is only
available as that: a driver. No manufacturer has yet produced a
loudspeaker with them, which means that if you want to try them you'll
have to build your own speaker. Not an easy thing to do, but if you
decide to do it anyway then a sealed cabinet is actually the easiest
to build and using a full range driver is a huge advantage as well,
since the crossover that is needed for a multi driver speaker is by
far the most complicated thing in loudspeaker design to get right.
Compared to that just putting a full range driver in a closed box is
simplicity itself.

My woodworking skills are minimal and I don't have a workshop, so I
needed some help with the cabinets. I decided to ask Wilmslow Audio in
Leicester, UK, to make me a kit for the cabinets, so that I only
needed to put them together, without the need for any sawing or
routing. They were very happy to help and produced a great kit from
which I was able to build a pair of excellent speakers. The only
comment I have on the cabinets is that the construction method has
the disadvantage that the corners aren't cosmetically perfect: there's
a small strip of MDF on show at each corner as the veneered surfaces
don't completely meet. I don't think this is a huge problem, but if you
want your speakers to look perfect you will have to try a different
solution. The construction is certainly solid and reliable, and
everything fitted with perfect precision.

I used the cabinet
design that SEAS provided online. There were two good reasons for
this. First, it was much easier than coming up with a new design
myself, and second SEAS actually used identical enclosures to develop
the drivers in, so they are more or less guaranteed to work well. The
design is for a 60 litre floorstander with extensive internal bracing.
The only change I requested was a thicker front panel: 22mm instead of
18mm. For the rest the cabinets were made precisely as specified by
SEAS. I added about 15 grams of wool per litre to the cabinets for
damping, and this seemed OK to me, even if the bass was on the dry
side. You could certainly experiment with less damping. SEAS claim
that these cabinets will give you a Q of about 0.8 without any damping
at all, which is a good value. With my added damping I should now have
about 0.7, which is generally considered to be close to optimal.

One more thing that became obvious while working on the cabinets is
the importance of suppressing internal reflections. Initially, I had
only put in the wool to dampen the enclosure as a whole. But the
speakers sounded shut in and the sound seemed to stick to them. I then
covered the inside of the top of the cabinets with acoustic foam, to
prevent reflections, and this cured the problem completely. The sound
was now more open and refined with the soundstage almost completely
disconnected from the cabinets. I was now experiencing the real
acoustics of the recording, instead of listening to a pair of boxes.

The spectral response curve for the Exotic drivers shows a clear
imbalance: the top three octaves are tilted upwards and the
reproduction without any measures to correct for this is therefore
very much dominated by the higher frequencies. This is not unusual for
such a design and has to do with the different cones responsible for
the lower and higher frequencies, I assume. The solution is to use a
simple filter, the design of which is provided by SEAS. It basically
looks very much like a baffle-step filter and consists of an inductor
and a resistor in parallel. This little circuit is then put in series
with the speaker and corrects the imbalance of the driver. I used a
0.68 Jantzen ribbon inductor with a Mills 15 Ohm resistor. I initially
used 12 Ohms ceramic resistors, but decided that reproduction was a
bit too bright for my taste and changed them for the 15 Ohm resistors.
Playing with these values will give you an opportunity to finetune the
speakers to your taste. What you will prefer will also depend on how
you place your speakers. When they are aimed at you directly there's
more high frequencies than when they are pointing slightly away. I
like to sit in the hot spot, with both of them firing almost straight
at me, and I found a higher resistor value beneficial for this.

The Exotic drivers feel extremely exposed when mounted in a cabinet.
Especially the little whizzer cone feels very delicate and protrudes
from the other cone in such a way that I feared for its safely, given
the presence of two small children in my household. After considerable
thought and some research I decided to have a pair of grilles
manufactured specially for these two drivers. It was an expensive
option, but the resulting peace of mind made it completely worth it.
The grilles were laser cut from 0.9mm stainless steel by Cutting
Technologies Ltd, Barnsley, UK. The cost was about £150 for the pair.
One of the grilles isn't completely flat when mounted, which is caused
by the heat involved in laser cutting and is difficult to prevent.
Perhaps water-jet cutting would have been a better option. Still, I think
they look quite good, and they are extremely effective too. I didn't hear
any difference after mounting the grilles, in spite of them ringing a
bit when I tap them with my finger.

The Exotic F8 drivers have a nominal impedance of 8 ohms and a
sensitivity of around 91 db/watt, which should make them a very
easy load for the amplifier. They are also 'valve-friendly',
something I will come back to later in this review. I really cannot
imagine an amp that wouldn't be able to drive these speakers, as
the sealed cabinets even make controlling the bass a doddle.
The cabinets are rather big, though, so you will need a bit of space
to accommodate them. The finished speakers are also quite heavy.

Sound

I have to be honest here and tell you that the SEAS Exotic F8 speakers
take a little bit of getting used to. They are definitely different
from your usual speaker and first impressions can be that they sound a
bit 'odd'. Bass is much dryer than with most ported speakers, and can
sound a bit thin in comparison. But, their main qualities are also
immediately clear: mostly an impressive transparency and immense
precision, coupled to a great top-to-bottom consistency and fantastic
dynamic expression.

What also
soon becomes obvious is that these speakers take no prisoners: they
ruthlessly reveal the properties of the electronics upstream, and the
recording especially. Bad recordings will sound bad, even if the music
on them also comes through very strongly. These speakers refuse to
prettify anything and just give it to you as it is. This is fantastic
with good recordings, but can indeed induce some discomfort with
lesser material. The thing is, these speakers are so engaging and
honest that you soon forget to listen to your system and just focus on
the performance. Once you start doing that, and you will, the fact
that they are almost too revealing becomes irrelevant and you just
enjoy the music.

I did use them with a small subwoofer, but that is mostly to fill in a
dip in the bass reproduction that is caused by my room. Bass simply
sounds more even with the sub, and ever so slightly fuller, but was
certainly adequate without it. If you like stronger bass from
the Exotic drivers you could try less damping material than I
used, or indeed combine them with a good subwoofer. The advantage of
dry and well controlled bass is that it is easier to integrate with a
sub, as the sub can now add what is missing while it can never take
away what is wrongly added.

The soundstage is impressive. Like with electrostats and most other
panel speakers the instruments just appear behind the speakers as if
they are actually there and the speakers have nothing to do with it.
It's a classic disappearing act and it produces a realism and
directness that immediately brings you to the performance, virtually
cutting out the system. When you focus on it you can still hear a
system working, of course, partly because the Exotics are so revealing
of the electronics feeding them, but also because these speakers are
certainly not perfect. They have their limitations, but with a good
recording they make you forget about those and bring a sense of
occasion that doesn't wear off, even after months. I don't always feel
like listening to music but the Exotics have that ability to keep you
listening for the whole evening, even if you initially had to force
yourself into it. One thing that really helps with this is the fact
that every recording sounds different, due to a lack of added
personality and colour by the SEAS drivers. This means that they are
uncannily able to reproduce the specific atmosphere of a performance
and bring you to a different environment with every disc. The flip side
of this honesty and transparency is that recordings that rely on a bit
of extra warmth or support from the system can now sound somewhat
stark and uninspiring. Specifically processed pop music suffers from
this. Another point is that these speakers are very sensitive to being
played at the right volume. Too low and they sound a bit thin, too
high and they start to lose their refinement. You also need to make
sure that the volume is consistent with the actual performance: a full
orchestra doesn't sound convincing at a low volume, and the Exotic
drivers make this extra clear.

Going back to my own Dynaudio Contour 1.8 mk2 speakers after a while
was a shocking experience. Their bass sounds quite boxy and over the
top compared to the SEAS. They also sound a lot softer and less alive,
almost boring in fact. It really took me about an hour to get used to
my own speakers again, and then I was still missing a lot of things
the SEAS are doing so well, like micro dynamics, precision and rhythm.
Compared to the life-like dynamics of the Exotics most multi-way
speakers sound a little bit blunted, so I cannot blame it on the
Dynaudio's, but the difference was much bigger than I expected.
The Dynaudios are more forgiving of less than optimal recordings, but
they also disappoint with really good recordings, mostly because of
their lack of control in the bass. And I'm using them with socks in
the ports! I do have to admit that some of these problems are caused
by my listening room, which is too small and too square for really
good bass reproduction. Still, the SEAS were doing a much, much better
job, albeit with the help of that small subwoofer.

I also took the Exotics to a friend, to be able to hear them in a
different system and room. My friend's room is much bigger than mine,
and also is acoustically better. His system is all Naim and his own
loudspeakers are the famous Living Voice Avatar OBX, which should
provide stiff competition for the SEAS. In spite of a different
system, and a very different room, the effect of replacing the Living
Voice speakers with the SEAS and then going back to the LV's a few
days later was quite comparable to my experiences with my Dynaudios.
Of course, the Living Voice speakers are much better and are sitting
in a room that really suits them, so the bass problems I have in my
room weren't happening here. But the SEAS still showed their midrange
qualities and their control and precision overall. Voices were
delicious and piano a treat. The only real downside was that the bass
wasn't strong enough for the room, and we didn't have the time to
adjust my friend's subwoofer to the SEAS. This was a shame, as a good
strong bass underpinning would have worked really well with the sound
that the Exotics were producing in my friend's room.
Compared to the
brilliant Scan Speak Revelator tweeters in the Living voice speakers,
the top end of the SEAS did lack a bit of sparkle, but to be honest
this didn't really bother me. Going back to the Avatars after
extensive exposure to the SEAS was an experience that reminded me of
the contrast with my own Dynaudios: compared to the SEAS Exotic other,
'normal', speakers do sound a bit soft, slightly inconsistent over the
frequency range and a little bit lumpy in the bass range. I do have to
admit that I would still prefer the Living Voice speakers to the SEAS
ones, if only because they are easier to live with. But I would still
be missing the SEAS, no doubt about it. One of our friends described
the SEAS as being a bit like a Harley Davidson motorbike: very very
good at a few things, but you would want to have one or two other bikes
next to it for the other things.

As part of my investigation I thought I'd also try these speakers with
valve amplification. That is their natural partner, after all. The
fact is, however, that I had never before used valve amplification in
my system. The reviews will follow, but I can already tell you that I
soon regretted not trying valves earlier, as I very much liked what I
heard. These speakers indeed work very well with valves. The first
amp I tried was the Icon Audio Stereo 40 mk3, an integrated push-pull
amplifier using KT88 valves and rated at 40 watts. The clearest
difference was in the bass, which was now fuller and warmer. This
could be the case because I perhaps overstuffed the cabinets a little
bit, making them slightly too dry in the bass. The lower damping
factor of the valve amp nicely compensates for that and the overall
balance was now spot on. The midrange benefitted too from the typical
valve richness which is extremely welcome with a speaker like this.
Even the top end now seems a bit more open and gained some clarity.
Especially piano now sounds better in the higher registers, with a
more natural tone and a more dynamic and sparkling sound. All in all I
think this speaker really should be used with a good valve amp, and
the Stereo 40 seems the perfect partner.

Then I was also able to borrow a 300B single ended triode amp from
Mike Cox, our new reviewer. This worked even better in many respects,
but was lacking somewhat in other areas. The sound is now even warmer
and richer, which is welcome, but the top end is positively muted. On
the other hand, and to my surprise, the dynamic qualities of the
midrange and top end seems to be even better than with the Icon Audio
and this 8 watt amplifier even works quite well at relatively high
volumes. It does feel like a step back in time, to drive a single
driver speaker with a 300B SET amp, but there's no denying that it
works and that the famous valve magic is present in spades!

The move from transistor amplification, my Usher R1.5 to be precise,
to valves made these speakers even more competitive with normal
speakers, I have to say. During the review period I also had a pair of
PMC speakers available, and the SEAS had no trouble beating them on
musicality, even if the PMC speakers scored higher on virtually every
hifi parameter. The combination with the Icon Audio Stereo 40 mk3 is
fantastic and actually exceeds my expectations of what was possible in
my room. In that light, all my earlier experiences with transistor
amps aren't really relevant anymore, even if the Exotics did
actually perform rather well with them. Switch to a valve amp,
however, and you can experience something really special. The
transparency, musicality, tonal purity, warmth and engagement that
this paring will produce is exceptional and very addictive. The best
amplifier and speaker combination I've had in my system, and by a long
way at that.

Conclusion

In summary I can say that these speakers aren't the easiest to live
with, but they can be hugely rewarding at times. When used with valve
amplification they really come into their own and produced the best
sound I've ever had coming from my system. Their main qualities are
musicality and coherence, and compared to these speakers most other
'multi-way' speakers sound mechanical and artificial. Another definite
talent is the transparency of the midrange and virtually everything
else sounds somewhat muted in the middle frequencies in comparison. In
combination these two properties make voices sound amazing: very
natural and very real. Bass is equally good, very precise but less
strong than with ported speakers. I found that a small sub really
helps, but you might want to also put less damping in yours than I did,
unless you are using valve amplification.

The only things that are a bit less that average for this price range
are the top end and the maximum volume. Both aren't bad, but most
speakers will have a bit more spark at the top and will go louder. The
treble is fine when the speakers are aimed straight at you, but much
less strong when toed out or in. This also means that the hot spot for
listening is rather small: these are single person speakers, really.
It also means that the off axis response lacks the upper frequencies,
making for a less than optimal dispersion. Because of this these are
more 'you are there' speakers rather than 'they are in your room'
ones, if you get the idea.

Perhaps the best thing about these speakers is the way they make you
focus on the music. When you hear musicians perform live, you're not
going to ask yourself how deep the bass is, or how transparent the
midrange, how crisp the treble, are you? These speakers do the same
thing. Who is going to worry about hifi parameters when you can almost
see that double bass right in front of you? And, just like with the
real thing, you might want to hear the performer in a better acoustic,
or from a better seat. But that is the point: you're still hearing a
performance, not a reproduction. Whatever they do wrong, the things
they do right make you forget about the errors.

In the end, what fascinates me most about these drivers is not just
how well they sound, and how coherent and musical they are, but also
the fact that they prove that there's not one single solution to
building a good loudspeaker. They are distinctly different to most
other speakers in the market, but just as valid and enjoyable as a
tool to bring music to life. They've not only entertained me, they
have also thought me something, and changed my perspective on audio.
They've even led me to valve amplifiers, and in combination these two
ancient technologies have brought new life to my hobby and made me
appreciate music more than ever. A loudspeaker cannot do much more
than that. Highly recommended, especially with valve amplification.